Effects of Iron-Oxide Nanoparticle Surface Chemistry on Uptake Kinetics and Cytotoxicity in CHO-K1 Cells

Comprehensive Analysis of the Potential Toxicity of Magnetic Iron Oxide Nanoparticles for Medical Applications: Cellular Mechanisms and Systemic Effects

Owing to recent advancements in nanotechnology, magnetic iron oxide nanoparticles (MNPs), particularly magnetite (Fe3O4) and maghemite (γ-Fe2O3), are currently widely employed in the field of medicine. These MNPs, characterized by their large specific surface area, potential for diverse functionalization, and magnetic properties, have found application in various medical domains, including tumor imaging (MRI), radiolabelling, internal radiotherapy, hyperthermia, gene therapy, drug delivery, and theranostics. However, ensuring the non-toxicity of MNPs when employed in medical practices is paramount. Thus, ongoing research endeavors are essential to comprehensively understand and address potential toxicological implications associated with their usage. This review aims to present the latest research and findings on assessing the potential toxicity of magnetic nanoparticles. It meticulously delineates the primary mechanisms of MNP toxicity at the cellular level, encompassing oxidative stress, genotoxic effects, disruption of the cytoskeleton, cell membrane perturbation, alterations in the cell cycle, dysregulation of gene expression, inflammatory response, disturbance in ion homeostasis, and interference with cell migration and mobility. Furthermore, the review expounds upon the potential impact of MNPs on various organs and systems, including the brain and nervous system, heart and circulatory system, liver, spleen, lymph nodes, skin, urinary, and reproductive systems.

Biomaterials functionalized with magnetic nanoparticles for tissue engineering: Between advantages and challenges

The integration of magnetic nanoparticles (MNPs) into biomaterials offers exciting opportunities for tissue engineering as they enable better control over cell guidance, release of bioactive factors and tissue maturation. Despite their potential, challenges such as the heterogeneity of MNPs, their cytotoxicity and the need for precise control of MNP`s properties hinder their widespread application. Overcoming these challenges will require new interdisciplinary efforts and technological advances, including the development of mathematical tools and additional elaborations to ensure the biocompatibility of MNPs.

To see or not to see: In vivo nanocarrier detection methods in the brain and their challenges

Nanoparticles have a great potential to significantly improve the delivery of therapeutics to the brain and may also be equipped with properties to investigate brain function. The brain, being a highly complex organ shielded by selective barriers, requires its own specialized detection system. However, a significant hurdle to achieve these goals is still the identification of individual nanoparticles within the brain with sufficient cellular, subcellular, and temporal resolution. This review aims to provide a comprehensive summary of the current knowledge on detection systems for tracking nanoparticles across the blood-brain barrier and within the brain. We discuss commonly employed in vivo and ex vivo nanoparticle identification and quantification methods, as well as various imaging modalities able to detect nanoparticles in the brain. Advantages and weaknesses of these modalities as well as the biological factors that must be considered when interpreting results obtained through nanotechnologies are summarized. Finally, we critically evaluate the prevailing limitations of existing technologies and explore potential solutions.

Toxicological Effects of Metal Nanoparticles Employed in Biomedicine: Biocompatibility, Clinical Trials, and Future Perspective

Metal nanoparticles play a crucial role in the medical industry due to its desirable properties such as antimicrobial activity, anti‐cancer property, and its application in disease diagnostics. These properties enable the nanoparticles to be used as efficient medical devices for various treatments as well as drug delivery systems. Despite all the positives, metal nanoparticles are known for causing toxicity in the living system. The toxicological effects of metal nanoparticles are due to their size, surface*e coating, and the dose administered. Therefore, it is important to study the toxic effects of these nanoparticles before they are used as medical devices for various treatments. This review focuses on the five major metal nanoparticles used in the medical field, namely; silver, gold, iron oxide, zinc oxide, and titanium dioxide nanoparticles. The non‐exhaustive review consists of an introduction to the toxicological effects of these nanoparticles, the biocompatibility, and the current and future clinical perspective on metal nanoparticles.

Gamma-Camera Direct Imaging of the Plasma and On/Intra Cellular Distribution of the 99mTc-DPD-Fe3O4 Dual-Modality Contrast Agent in Peripheral Human Blood

The radiolabeled iron oxide nanoparticles constitute an attractive choice to be used as dual-modality contrast agents (DMCAs) in nuclear medical diagnosis, due to their ability to combine the benefits of two imaging modalities, for instance single photon emission computed tomography (SPECT) with magnetic resonance imaging (MRI). Before the use of any DMCA, the investigation of its plasma extra- and on/intra cellular distribution in peripheral human blood is of paramount importance. Here, we focus on the in vitro investigation of the distribution of 99mTc-DPD-Fe3O4 DMCA in donated peripheral human blood (the ligand 2-3-dicarboxypropane-1-1-diphosphonic-acid is denoted as DPD). Initially, we described the experimental methods we performed for the radiosynthesis of the 99mTc-DPD-Fe3O4, the preparation of whole blood and blood plasma samples, and their incubation conditions with 99mTc-DPD-Fe3O4. More importantly, we employed a gamma-camera apparatus for the direct imaging of the 99mTc-DPD-Fe3O4-loaded whole blood and blood plasma samples when subjected to specialized centrifugation protocols. The direct comparison of the gamma-camera data obtained at the exact same samples before and after their centrifugation enabled us to clearly identify the distribution of the 99mTc-DPD-Fe3O4 in the two components, plasma and cells, of peripheral human blood.

Nanoparticles as Drug Delivery Systems: A Review of the Implication of Nanoparticles' Physicochemical Properties on Responses in Biological Systems

In the last four decades, nanotechnology has gained momentum with no sign of slowing down. The application of inventions or products from nanotechnology has revolutionised all aspects of everyday life ranging from medical applications to its impact on the food industry. Nanoparticles have made it possible to significantly extend the shelf lives of food product, improve intracellular delivery of hydrophobic drugs and improve the efficacy of specific therapeutics such as anticancer agents. As a consequence, nanotechnology has not only impacted the global standard of living but has also impacted the global economy. In this review, the characteristics of nanoparticles that confers them with suitable and potentially toxic biological effects, as well as their applications in different biological fields and nanoparticle-based drugs and delivery systems in biomedicine including nano-based drugs currently approved by the U.S. Food and Drug Administration (FDA) are discussed. The possible consequence of continuous exposure to nanoparticles due to the increased use of nanotechnology and possible solution is also highlighted.

Potential Environmental and Health Implications from the Scaled-Up Production and Disposal of Nanomaterials Used in Biosensors

Biosensors often combine biological recognition elements with nanomaterials of varying compositions and dimensions to facilitate or enhance the operating mechanism of the device. While incorporating nanomaterials is beneficial to developing high-performance biosensors, at the stages of scale-up and disposal, it may lead to the unmanaged release of toxic nanomaterials. Here we attempt to foster connections between the domains of biosensors development and human and environmental toxicology to encourage a holistic approach to the development and scale-up of biosensors. We begin by exploring the toxicity of nanomaterials commonly used in biosensor design. From our analysis, we introduce five factors with a role in nanotoxicity that should be considered at the biosensor development stages to better manage toxicity. Finally, we contextualize the discussion by presenting the relevant stages and routes of exposure in the biosensor life cycle. Our review found little consensus on how the factors presented govern nanomaterial toxicity, especially in composite and alloyed nanomaterials. To bridge the current gap in understanding and mitigate the risks of uncontrolled nanomaterial release, we advocate for greater collaboration through a precautionary One Health approach to future development and a movement towards a circular approach to biosensor use and disposal.

Nanoparticle-Based Delivery Systems for Vaccines

Vaccination is still the most cost-effective way to combat infectious illnesses. Conventional vaccinations may have low immunogenicity and, in most situations, only provide partial protection. A new class of nanoparticle-based vaccinations has shown considerable promise in addressing the majority of the shortcomings of traditional and subunit vaccines. This is due to recent breakthroughs in chemical and biological engineering, which allow for the exact regulation of nanoparticle size, shape, functionality, and surface characteristics, resulting in improved antigen presentation and robust immunogenicity. A blend of physicochemical, immunological, and toxicological experiments can be used to accurately characterize nanovaccines. This narrative review will provide an overview of the current scenario of the nanovaccine.

Evaluation of cellular stress responses in magnetomotive ultrasound

Early and accurate diagnoses are important for successful cancer treatment. Lymph node involvement is often critical, and magnetomotive ultrasound (MMUS) has been proposed for its detection and characterization. MMUS relies on a magnetic contrast agent, for example, iron oxide nanoparticles, delivered to the tissue of interest, magnetically set in motion and detected using ultrasound. The magneto-mechanical interaction has not previously been evaluated on a cellular level. Here we demonstrate uptake and dose-dependent retention of magnetic nanoparticles in two human adenocarcinoma cell lines, with <10% cytotoxicity which did not increase following magnetic excitation. Further, the oxidative stress levels were not affected by magnetic particles or force. Thus, we found no evidence of adverse effects from the magneto-mechanical interactions under these conditions.

Effects of PEG Chain Length on Relaxometric Properties of Iron Oxide Nanoparticles-Based MRI Contrast Agent

Iron oxide nanoparticles (IONPs) as magnetic resonance imaging (MRI) contrast agents have received considerable interest due to their superior magnetic properties. To increase the biocompatibility and blood circulation time, polyethylene glycol (PEG) is usually chosen to decorate IONPs. Although the surface effect induced by the PEGylation has an impact on the relaxometric properties of IONPs and can subsequently affect the imaging results, the occurrence of particle aggregation has troubled researchers to deeply explore this correlation. To shed light on this relationship, three diphosphonate PEGs with molecular weights of 1000, 2000, and 5000 Da were used to replace the hydrophobic oleate ligands of 3.6 nm and 10.9 nm IONPs. Then, the contrast enhancement properties of the resultant “aggregation-free” nanoparticles were carefully evaluated. Moreover, related theories were adopted to predict certain properties of IONPs and to compare with the experimental data, as well as obtain profound knowledge about the impacts of the PEG chain length on transverse relaxivity (r₂) and longitudinal relaxivity (r₁). It was found that r₂ and the saturated magnetization of the IONPs, independent of particle size, was closely related to the chain length of PEG. The results unveiled the correlation between the chain length of the coated PEG and the relaxometric properties of IONPs, providing valuable information which might hold great promise in designing optimized, high-performance IONPs for MRI-related applications.

Charge-Modulated Synthesis of Highly Stable Iron Oxide Nanoparticles for In Vitro and In Vivo Toxicity Evaluation

The surface charge of iron oxide nanoparticles (IONPs) plays a critical role in the interactions between nanoparticles and biological components, which significantly affects their toxicity in vitro and in vivo. In this study, we synthesized three differently charged IONPs (negative, neutral, and positive) based on catechol-derived dopamine, polyethylene glycol, carboxylic acid, and amine groups, via reversible addition-fragmentation chain transfer-mediated polymerization (RAFT polymerization) and ligand exchange. The zeta potentials of the negative, neutral, and positive IONPs were -39, -0.6, and +32 mV, respectively, and all three IONPs showed long-term colloidal stability for three months in an aqueous solution without agglomeration. The cytotoxicity of the IONPs was studied by analyzing cell viability and morphological alteration in three human cell lines, A549, Huh-7, and SH-SY5Y. Neither IONP caused significant cellular damage in any of the three cell lines. Furthermore, the IONPs showed no acute toxicity in BALB/c mice, in hematological and histological analyses. These results indicate that our charged IONPs, having high colloidal stability and biocompatibility, are viable for bio-applications.

Ovarian toxicity of nanoparticles

The ovary is a highly important organ for female reproduction. The main functions include sex steroid hormone synthesis, follicular development, and achievement of oocyte meiotic and development competence for proper fertilization. Nanoparticle (NP) exposure is becoming unavoidable because of its wide use in different products, including cosmetics, food, health, and personal care products. Studies examining different nonreproductive tissues or systems have shown that characteristics such as the size, shape, core material, agglomeration, and dissolution influence the effects of NPs. However, most studies evaluating NP-mediated reproductive toxicity have paid little or no attention to the influence of the physicochemical characteristics of NP on the observed effects. As accumulating evidence indicates that NP may reach the ovary to impair proper functions, this review summarizes the available data on NP accumulation in ovarian tissue, as well as data describing toxicity to ovarian functions, including sex steroid hormone production, follicular development, oocyte quality, and fertility. Due to their toxicological relevance, this review also describes the main physicochemical characteristics involved in NP toxicity and the importance of considering NP physicochemical characteristics as factors influencing the ovarian toxicity of NPs. Finally, this review summarizes the main mechanisms of toxicity described in ovarian cells.

Magnetic characterization of paramagnetic reagents by particle tracking velocimetry

Magnetic particle characterization determines the quality of magnetic particles and is of great importance in particle technology, drug delivery, cell separation, in vivo diagnostics, and other biomedical applications. The quality of the sample depends on the particle size, intrinsic magnetic properties of the particles, and the uniformity of these properties. A commercial particle tracking velocimeter was used to record and capture dark field images of particle trajectories in an applied isodynamic magnetic field. The calibrated particle size, magnetophoretic mobility, and additional image data were collected for each magnetic bead imaged. Using twenty-one different de-identified calibration beads and transmission electron microscopy to validate the vendor-reported particle size enabled the estimation of intrinsic magnetic properties, namely, apparent magnetic susceptibility and saturation magnetization, of individual paramagnetic particles. The distributions of volume magnetic susceptibility based on the magnetophoretic mobility and size of the particle for different magnetic beads were determined and displayed as two-parameter distributions. The measured apparent susceptibility and saturation magnetization were found to be directly proportional to the percentage of iron oxide in the reagent particles.

Silicone Oil-Based Nanoadjuvants as Candidates for a New Formulation of Intranasal Vaccines

Many conventional vaccines are administered via a needle injection, while most pathogens primarily invade the host via mucosal surfaces. Moreover, protective IgA antibodies are insufficiently induced by parenteral vaccines. Mucosal immunity induces both local and systemic response to pathogens and typically lasts for long periods of time. Therefore, vaccination via mucosal routes has been increasingly explored. However, mucosal vaccines require potent adjuvants to become efficacious. Despite many efforts to develop safe and robust adjuvants for mucosal vaccines, only a few have been approved for use in human formulations. The aim of our study was to design, develop and characterize new silicone oil-based nanoadjuvant candidates for intranasal vaccines with potential to become mucosal adjuvants. We have developed an array of nanoadjuvant candidates (NACs), based on well-defined ingredients. NAC1, 2 and 3 are based on silicone oil, but differ in the used detergents and organic solvents, which results in variations in their droplet size and zeta potential. NACs' cytotoxicity, Tumor Necrosis Factor α (TNF-α) induction and their effect on antigen engulfment by immune cells were tested in vitro. Adjuvant properties of NACs were verified by intranasal vaccination of mice together with ovalbumin (OVA). NACs show remarkable stability and do not require any special storage conditions. They exhibit bio-adhesiveness and influence the degree of model protein engulfment by epithelial cells. Moreover, they induce high specific anti-OVA IgG antibody titers after two intranasal administrations. Nanoadjuvant candidates composed of silicone oil and cationic detergents are stable, exhibit remarkable adjuvant properties and can be used as adjuvants for intranasal immunization.

Shedding Light on Metal-Based Nanoparticles in Zebrafish by Computed Tomography with Micrometer Resolution

Metal-based nanoparticles are clinically used for diagnostic and therapeutic applications. After parenteral administration, they will distribute throughout different organs. Quantification of their distribution within tissues in the 3D space, however, remains a challenge owing to the small particle diameter. In this study, synchrotron radiation-based hard X-ray tomography (SRμCT) in absorption and phase contrast modes is evaluated for the localization of superparamagnetic iron oxide nanoparticles (SPIONs) in soft tissues based on their electron density and X-ray attenuation. Biodistribution of SPIONs is studied using zebrafish embryos as a vertebrate screening model. This label-free approach gives rise to an isotropic, 3D, direct space visualization of the entire 2.5 mm-long animal with a spatial resolution of around 2 µm. High resolution image stacks are available on a dedicated internet page (http://zebrafish.pharma-te.ch). X-ray tomography is combined with physico-chemical characterization and cellular uptake studies to confirm the safety and effectiveness of protective SPION coatings. It is demonstrated that SRμCT provides unprecedented insights into the zebrafish embryo anatomy and tissue distribution of label-free metal oxide nanoparticles.

Rotating Magnetic Nanoparticle Clusters as Microdevices for Drug Delivery

BACKGROUND

Magnetic nanoparticles (MNPs) hold promise for enhancing delivery of therapeutic agents, either through direct binding or by functioning as miniature propellers. Fluid-filled conduits and reservoirs within the body offer avenues for MNP-enhanced drug delivery. MNP clusters can be rotated and moved across surfaces at clinically relevant distances in response to a rotating magnet. Limited data are available regarding issues affecting MNP delivery by this mechanism, such as adhesion to a cellular wall. Research reported here was initiated to better understand the fundamental principles important for successful implementation of rotational magnetic drug targeting (rMDT).

METHODS

Translational movements of four different iron oxide MNPs were tested, in response to rotation (3 Hz) of a neodymium-boron-iron permanent magnet. MNP clusters moved along biomimetic channels of a custom-made acrylic tray, by surface walking. The effects of different distances and cellular coatings on MNP velocity were analyzed using videography. Dyes (as drug surrogates) and the drug etoposide were transported by rotating MNPs along channels over a 10 cm distance.

RESULTS

MNP translational velocities could be predicted from magnetic separation times. Changes in distance or orientation from the magnet produced alterations in MNP velocities. Mean velocities of the fastest MNPs over HeLa, U251, U87, and E297 cells were 0.24 ± 0.02, 0.26 ± 0.02, 0.28 ± 0.01, and 0.18 ± 0.03 cm/sec, respectively. U138 cells showed marked MNP adherence and an 87.1% velocity reduction at 5.5 cm along the channel. Dye delivery helped visualize the effects of MNPs as microdevices for drug delivery. Dye delivery by MNP clusters was 21.7 times faster than by diffusion. MNPs successfully accelerated etoposide delivery, with retention of chemotherapeutic effect.

CONCLUSION

The in vitro system described here facilitates side-by-side comparisons of drug delivery by rotating MNP clusters, on a human scale. Such microdevices have the potential for augmenting drug delivery in a variety of clinical settings, as proposed.

Mechanisms for cellular uptake of nanosized clinical MRI contrast agents

Engineered Nanomaterials (NMs), such as Superparamagnetic Iron Oxide Nanoparticles (SPIONs), offer significant benefits in a wide range of applications, including cancer diagnostic and therapeutic strategies. However, the use of NMs in biomedicine raises safety concerns due to lack of knowledge on possible biological interactions and effects. The initial basis for using SPIONs as biomedical MRI contrast enhancement agents was the idea that they are selectively taken up by macrophage cells, and not by the surrounding cancer cells. To investigate this claim, we analyzed the uptake of SPIONs into well-established cancer cell models and benchmarked this against a common macrophage cell model. In combination with fluorescent labeling of compartments and siRNA silencing of various proteins involved in common endocytic pathways, the mechanisms of internalization of SPIONs in these cell types has been ascertained utilizing reflectance confocal microscopy. Caveolar mediated endocytosis and macropinocytosis are both implicated in SPION uptake into cancer cells, whereas in macrophage cells, a clathrin-dependant route appears to predominate. Colocalization studies confirmed the eventual fate of SPIONs as accumulation in the degradative lysosomes. Dissolution of the SPIONs within the lysosomal environment has also been determined, allowing a fuller understanding of the cellular interactions, uptake, trafficking and effects of SPIONs within a variety of cancer cells and macrophages. Overall, the behavior of SPIONS in non-phagocytotic cell lines is broadly similar to that in the specialist macrophage cells, although some differences in the uptake patterns are apparent.

Development of Ga-68 labeled, biotinylated thiosemicarbazone dextran-coated iron oxide nanoparticles as multimodal PET/MRI probe

Bifunctional biotinylated thiosemicarbazone dextran-coated iron oxide Nanoparticles (NPs) were fabricated. Aldehyde groups of the oxidized dextran-coating layer were utilized to conjugate biotin as a tumor-targeting agent and thiosemicarbazide as a cation chelator on the surface of NPs. The final product was characterized for physicochemical and biological properties. It was compatible with red blood cells and did not change the blood coagulation time. It also showed a significantly enhanced affinity to biotin receptor-positive 4T1 cells compared to non-biotinylated ones. The r2 relaxivity coefficient value of the final product was 110.2 mM^-1 s^-1. Although biotinylated NPs were easily radiolabeled with Ga-68 at room temperature, the stable radiolabeled NPs were achieved at a higher temperature (60 °C). The radiolabeled NPs were majorly accumulated in the liver and spleen. However, about 5.4% ID/g of the radiolabeled NPs was accumulated within the 4T1 tumor site. Blocking studies was performed by the biotin molecules pre-injection showed uptake reduction in the 4T1 tumor (about 1.1% ID/g). The radiolabeled NPs could be used for the early detection of biotin receptor-positive tumors via PET-MRI.

Evaluation of cytotoxicity and genotoxicity induced by oleic acid-coated iron oxide nanoparticles in human astrocytes

Iron oxide nanoparticles (ION) are gaining importance as diagnostic and therapeutic tool of central nervous system diseases. Although oleic acid-coated ION (O-ION) have been described as stable and biocompatible, their potential neurotoxicity was scarcely evaluated in human nervous cells so far. The primary aim of this work was to assess the molecular and cellular effects of O-ION on human astrocytes (A172 cells) under different experimental conditions. An extensive set of cyto- and genotoxicity tests was carried out, including lactate dehydrogenase release assay, cell cycle alterations, and cell death production, as well as comet assay, γH2AX assay, and micronucleus (MN) test, considering also iron ion release capacity and alterations in DNA repair ability. Results showed a moderate cytotoxicity related to cell cycle arrest and cell death promotion, regardless of serum presence. O-ION induced genotoxic effects, namely primary DNA damage, as detected by the comet assay and H2AX phosphorylation, but A172 cells were able to repair this particular damage because no chromosome alterations were found (confirmed by MN test results). Accordingly, no effects on the DNA repair ability were observed. The presence of serum proteins did not influence O-ION toxicity. Iron ions released from the O-ION surface seemed not to be responsible for the cytotoxic and genotoxic effects observed. Environ. Mol. Mutagen. 2019. © 2019 Wiley Periodicals, Inc.

Synthesis of Sub 3 nm-Sized Uniform Magnetite Nanoparticles Using Reverse Micelle Method for Biomedical Application

We report a synthetic method for small and uniform Fe3O4 (magnetite) nanoparticles under mild conditions. Spherical sub-3 nm-sized magnetite nanoparticles were prepared via reverse micelles composed of oleylamine, F127, xylene, and water for the reaction of iron(III) stearate with hydrazine at a reaction temperature of 90 °C in air atmosphere. These synthesized magnetite nanoparticles exhibited good size uniformity. By controlling experimental conditions, we could easily control both size and size uniformity of these magnetite nanoparticles. We further investigated whether Fe3O4 could be used in biomedical applications. Cytotoxicity of Fe3O4 was evaluated with human adipose-derived stem cells (hADSCs). Our results showed that the number of hADSCs did not significantly decrease when these cells were treated with Fe3O4 nanoparticles at a concentration of up to 9 μg/mL. Apoptotic activity and cell proliferation of hADSCs treated with Fe3O4 nanoparticles were similar to those of hADSCs without any treatment. This novel method could be used for synthesizing uniform and biocompatible Fe3O4 nanoparticles with further biomedical applications.

Engineered superparamagnetic iron oxide nanoparticles (SPIONs) for dual-modality imaging of intracranial glioblastoma via EGFRvIII targeting

In this work, a peptide-modified, biodegradable, nontoxic, brain-tumor-targeting nanoprobe based on superparamagnetic iron oxide nanoparticles (SPIONs) (which have been commonly used as T ₂-weighted magnetic resonance (MR) contrast agents) was successfully synthesized and applied for accurate molecular MR imaging and sensitive optical imaging. PEPHC1, a short peptide which can specifically bind to epidermal growth factor receptor variant III (EGFRvIII) that is overexpressed in glioblastoma, was conjugated with SPIONs to construct the nanoprobe. Both in vitro and in vivo MR and optical imaging demonstrated that the as-constructed nanoprobe was effective and sensitive for tumor targeting with desirable biosafety. Given its desirable properties such as a 100 nm diameter (capable of penetration of the blood-brain barrier) and bimodal imaging capability, this novel and versatile multimodal nanoprobe could bring a new perspective for elucidating intracranial glioblastoma preoperative diagnosis and the accuracy of tumor resection.

Novel method for rapid toxicity screening of magnetic nanoparticles

Iron oxide nanoparticles have attracted a great deal of research interest and have been widely used in bioscience and clinical research including as contrast agents for magnetic resonance imaging, hyperthermia and magnetic field assisted radionuclide therapy. It is therefore important to develop methods, which can provide high-throughput screening of biological responses that can predict toxicity. The use of nanoelectrodes for single cell analysis can play a vital role in this process by providing relatively fast, comprehensive, and cost-effective assessment of cellular responses. We have developed a new method for in vitro study of the toxicity of magnetic nanoparticles (NP) based on the measurement of intracellular reactive oxygen species (ROS) by a novel nanoelectrode. Previous studies have suggested that ROS generation is frequently observed with NP toxicity. We have developed a stable probe for measuring intracellular ROS using platinized carbon nanoelectrodes with a cavity on the tip integrated into a micromanipulator on an upright microscope. Our results show a significant difference for intracellular levels of ROS measured in HEK293 and LNCaP cancer cells before and after exposure to 10 nm size iron oxide NP. These results are markedly different from ROS measured after cell incubation with the same concentration of NP using standard methods where no differences have been detected. In summary we have developed a label-free method for assessing nanoparticle toxicity using the rapid (less than 30 minutes) measurement of ROS with a novel nanoelectrode.

Toxicity of Metal Oxide Nanoparticles

In the recent times, nanomaterials are used in many sectors of science, medicine and industry, without revealing its toxic effects. Thus, it is in urgent need for exploring the toxicity along with the application of such useful nanomaterials. Nanomaterials are categorized with a particle size of 1-100 nm. They have gained increasing attention because of their novel properties, including a large specific surface area and high reaction activity. The various fundamental and practical applications of nanomaterials include drug delivery, cell imaging, and cancer therapy. Nanosized semiconductors have their versatile applications in different areas such as catalysts, sensors, photoelectronic devices, highly functional and effective devices etc. Metal oxides contribute in many areas of chemistry, physics and materials science. Mechanism of toxicity of metal oxide nanoparticles can occur by different methods like oxidative stress, co-ordination effects, non-homeostasis effects, genotoxicity and others. Factors that affect the metal oxide nanoparticles were size, dissolution and exposure routes. This chapter will explain elaborately the toxicity of metal oxide nano structures in living beings and their effect in ecosystem.

Toxicity Assessment in the Nanoparticle Era

The wide use of engineered nanomaterials in many fields, ranging from biomedical, agriculture, environment, cosmetic, urged the scientific community to understand the processes behind their potential toxicity, in order to develop new strategies for human safety. As a matter of fact, there is a big discrepancy between the increased classes of nanoparticles and the consequent applications versus their toxicity assessment. Nanotoxicology is defined as the science that studies the effects of engineered nanodevices and nanostructures in living organisms. This chapter analyzes the physico-chemical properties of the most used nanoparticles, the way they enter the living organism and their cytoxicity mechanisms at cellular exposure level. Moreover, the current state of nanoparticles risk assessment is reported and analyzed.

Bone marrow mesenchymal stem cell repair of cyclophosphamide-induced ovarian insufficiency in a mouse model

Objective

Attempting in vivo healing of cyclophosphamide-induced ovarian insufficiency in a mouse model using bone marrow mesenchymal stem cells (BMMSCs).

Methods

Female BALB/c white mice were used to prepare a model for premature ovarian failure by single intraperitoneal injection of cyclophosphamide (80 mg/kg). Ten mice were injected with BMMSCs and then sacrificed after 21 days for morphometric evaluation of the ovaries. Hormonal profile was evaluated while mice were being sacrificed. Another 10 mice were left for natural breeding with male mice, and 5 of these were injected with BMMSCs. Oocyte-like structures were obtained from 3 mice and were subjected to in vitro fertilization/intracytoplasmic sperm injection.

Results

Morphometric analysis of the ovaries demonstrated the presence of newly formed primordial follicles. Contribution of MSCs to the formation of these follicles was proven by a labeling technique. There was a drop in estradiol and rise in follicle-stimulating hormone levels, followed by resumption of the hormonal levels to near normal 21 days after MSCs therapy. The 5 mice that were injected with MSCs became pregnant after natural breeding. Fertilization and further division was reported in 5 oocytes subjected to intracytoplasmic sperm injection, but division did not continue.

Conclusion

From this proof-of-concept trial, we can say that healing of damaged ovaries after chemotherapy in mice is possible using in vivo therapy with BMMSCs. This should open the gate for a series of animal studies that test the possibility of in vitro maturation of germinal epithelium of the ovary into mature oocytes.

Chelating agents as coating molecules for iron oxide nanoparticles

Iron oxide nanoparticles coated with chelating agents with different numbers of –COOH dentates (2 to 5) behave differently.

Intracellular accumulation and immunological responses of lipid modified magnetic iron nanoparticles in mouse antigen processing cells

Lipid modified magnetic nanoparticles could enhance the intracellular accumulation and immune responses of mouse antigen processing cells.

Are iron oxide nanoparticles safe? Current knowledge and future perspectives

Due to their unique physicochemical properties, including superparamagnetism, iron oxide nanoparticles (ION) have a number of interesting applications, especially in the biomedical field, that make them one of the most fascinating nanomaterials. They are used as contrast agents for magnetic resonance imaging, in targeted drug delivery, and for induced hyperthermia cancer treatments. Together with these valuable uses, concerns regarding the onset of unexpected adverse health effects following exposure have been also raised. Nevertheless, despite the numerous ION purposes being explored, currently available information on their potential toxicity is still scarce and controversial data have been reported. Although ION have traditionally been considered as biocompatible - mainly on the basis of viability tests results - influence of nanoparticle surface coating, size, or dose, and of other experimental factors such as treatment time or cell type, has been demonstrated to be important for ION in vitro toxicity manifestation. In vivo studies have shown distribution of ION to different tissues and organs, including brain after passing the blood-brain barrier; nevertheless results from acute toxicity, genotoxicity, immunotoxicity, neurotoxicity and reproductive toxicity investigations in different animal models do not provide a clear overview on ION safety yet, and epidemiological studies are almost inexistent. Much work has still to be done to fully understand how these nanomaterials interact with cellular systems and what, if any, potential adverse health consequences can derive from ION exposure.

Intracellular imaging of quantum dots, gold, and iron oxide nanoparticles with associated endocytic pathways

Metallic nanoparticles (NP) have been used for biomedical applications especially for imaging. Compared to nonmetallic NP, metallic NP provide high contrast images because of their optical light scattering, magnetic resonance, X-ray absorption, or other physicochemical properties. In this review, a series of in vitro imaging techniques for metallic NP will be introduced, meanwhile their strengths and weaknesses will be discussed. By utilizing these imaging methods, the cellular uptake of metallic NP can be easily visualized to better understand the endocytic mechanisms of NP intracellular delivery. Several types of metallic NP that are used for imaging or as contrast agents such as quantum dots, gold, iron oxide, and other metallic NP will be presented. Cellular uptake of metallic NP and associated endocytic mechanisms highly depends upon the NP size, charge, surface coating, shape, or other factors such as cell type, cell differentiation status, cell surface status, external forces, protein binding, temperature, and the biological milieu. Classical endocytic routes such as lipid raft-mediated pathways, clathrin or caveolae-mediated pathways, macropinocytosis, and phagocytosis have been investigated, yet there is still a demand to determine other endocytic pathways. Knowing the different methodologies used to determine the endocytic pathways will increase the understanding of NP toxicity, cancer cell targeting, and imaging, so that surface coatings can be created for efficient cell uptake of metallic NP with minimal cytotoxicity WIREs Nanomed Nanobiotechnol 2017, 9:e1419. doi: 10.1002/wnan.1419 For further resources related to this article, please visit the WIREs website.